# Helius LaserStream (Carbon 2.0) > Stream accounts, transactions and blocks from Helius LaserStream gRPC, with automatic slot replay after a reconnect. `LaserStreamGeyserClient` subscribes to Helius LaserStream, a hosted gRPC service that speaks the Yellowstone protocol, and emits account and transaction updates. Unlike the [Yellowstone datasource](https://carbon.sevenlabs.org/datasources/yellowstone-grpc.md), it tracks the last slot it saw and asks LaserStream to replay from that slot after a reconnect. Use it for real-time indexing on Helius when gaps after a disconnect are not acceptable. | | | | -------- | ------------------------------------------------------------------------------------------------------------------------------------------------------ | | Crate | `carbon-helius-laserstream-datasource` 2.0.0 | | Install | `cargo add carbon-helius-laserstream-datasource@2.0.0` | | Emits | `AccountUpdate`, `AccountDeletion`, `Transaction` | | Mode | Live, with replay from a recent slot. Runs until cancelled or until reconnects keep failing. | | Provider | A Helius API key on a plan that includes LaserStream, and a regional LaserStream endpoint such as `https://laserstream-mainnet-ewr.helius-rpc.com`. | | API docs | [docs.rs](https://docs.rs/carbon-helius-laserstream-datasource/2.0.0/carbon_helius_laserstream_datasource/) | | Source | [`datasources/helius-laserstream-datasource`](https://github.com/sevenlabs-hq/carbon/blob/v2.0.0/datasources/helius-laserstream-datasource/src/lib.rs) | ## Quick example This program streams confirmed, successful Orca Whirlpool transactions and prints each `swapV2`. It compiles as shown; to run it, set `LASERSTREAM_URL` and `HELIUS_API_KEY`. ```sh cargo new laserstream && cd laserstream cargo add carbon-core@2.0.0 carbon-log-metrics@2.0.0 carbon-orca-whirlpool-decoder@2.0.0 carbon-helius-laserstream-datasource@2.0.0 cargo add yellowstone-grpc-proto@=12.7.0 cargo add tokio@1 --features full cargo add env_logger@0.11 log@0.4 ``` `src/main.rs`: ```rust use { carbon_core::{ error::CarbonResult, instruction::InstructionProcessorInputType, pipeline::Pipeline, processor::Processor, }, carbon_helius_laserstream_datasource::{ BlockFilters, LaserStreamClientConfig, LaserStreamGeyserClient, }, carbon_log_metrics::LogMetrics, carbon_orca_whirlpool_decoder::{ instructions::OrcaWhirlpoolInstruction, OrcaWhirlpoolDecoder, PROGRAM_ID, }, std::{collections::HashMap, env, sync::Arc}, yellowstone_grpc_proto::geyser::{CommitmentLevel, SubscribeRequestFilterTransactions}, }; #[tokio::main] async fn main() -> CarbonResult<()> { env_logger::init(); let mut transaction_filters = HashMap::new(); transaction_filters.insert( "orca_whirlpool".to_string(), SubscribeRequestFilterTransactions { vote: Some(false), failed: Some(false), account_include: vec![PROGRAM_ID.to_string()], ..Default::default() }, ); let datasource = LaserStreamGeyserClient::new( env::var("LASERSTREAM_URL").expect("LASERSTREAM_URL must be set"), Some(env::var("HELIUS_API_KEY").expect("HELIUS_API_KEY must be set")), Some(CommitmentLevel::Confirmed), HashMap::new(), // account filters transaction_filters, BlockFilters::default(), LaserStreamClientConfig::default(), // replay_enabled: true ); Pipeline::builder() .datasource(datasource) .metrics(Arc::new(LogMetrics::new())) .instruction(OrcaWhirlpoolDecoder, SwapLogger) .build()? .run() .await } struct SwapLogger; impl Processor> for SwapLogger { async fn process( &mut self, input: &InstructionProcessorInputType<'_, OrcaWhirlpoolInstruction>, ) -> CarbonResult<()> { let tx = &input.metadata.transaction_metadata; if let OrcaWhirlpoolInstruction::SwapV2 { data, accounts, .. } = input.decoded_instruction { println!("slot {} swapV2 pool={} amount={}", tx.slot, accounts.whirlpool, data.amount); } Ok(()) } } ``` ```sh LASERSTREAM_URL=https://laserstream-mainnet-ewr.helius-rpc.com HELIUS_API_KEY=your-helius-api-key RUST_LOG=info cargo run ``` Each matching swap prints one `slot … swapV2 pool=… amount=…` line. The [Stream with LaserStream](https://carbon.sevenlabs.org/guides/stream-with-laserstream.md) guide covers endpoints and keys. ## Configuration ### `LaserStreamGeyserClient::new` ```rust pub const fn new( endpoint: String, x_token: Option, commitment: Option, account_filters: HashMap, transaction_filters: HashMap, block_filters: BlockFilters, geyser_config: LaserStreamClientConfig, ) -> Self ``` | Parameter | Type | Meaning | | --------------------- | ----------------------------------------------------- | ------------------------------------------------------------------------------------------------------------------------------------------------ | | `endpoint` | `String` | LaserStream gRPC URL for your region. | | `x_token` | `Option` | Your Helius API key, sent as `x-token`. | | `commitment` | `Option` | `Processed`, `Confirmed` or `Finalized`. Also decides how far back replay starts (see below). | | `account_filters` | `HashMap` | Named account filters, as for [Yellowstone](https://carbon.sevenlabs.org/datasources/yellowstone-grpc.md#configuration). | | `transaction_filters` | `HashMap` | Named transaction filters, as for Yellowstone. | | `block_filters` | `BlockFilters` | `filters: HashMap` and `failed_transactions: Option` (`None` keeps failed transactions from blocks). | | `geyser_config` | `LaserStreamClientConfig` | Connection and replay settings. | There is no disconnect notifier or stream timeout on this datasource. ### `LaserStreamClientConfig` ```rust pub const fn new( compression: Option, connect_timeout: Option, timeout: Option, max_decoding_message_size: Option, tls_config: Option, tcp_nodelay: Option, replay_enabled: bool, from_slot: Option, ) -> Self ``` | Field | Type | Default | Meaning | | --------------------------- | ----------------------------- | -------------------------------- | ----------------------------------------------------------------------------------------------------------------------------------------- | | `compression` | `Option` | `None` | Send and accept compressed messages. | | `connect_timeout` | `Option` | 15 s | Connection timeout. | | `timeout` | `Option` | 15 s | Request timeout. | | `max_decoding_message_size` | `Option` | `None` (client default) | Raise it if large messages fail to decode. | | `tls_config` | `Option` | `None` (system and webpki roots) | Custom TLS configuration. | | `tcp_nodelay` | `Option` | `None` | Set `TCP_NODELAY`. | | `replay_enabled` | `bool` | `true` | Track slots and resume from the last one after a reconnect. | | `from_slot` | `Option` | `None` | Start the first subscription at this past slot. **Only honoured when `replay_enabled` is `true`**; with replay off it is reset to `None`. | To start from a recent past slot: ```rust let geyser_config = LaserStreamClientConfig { from_slot: Some(467_000_000), ..LaserStreamClientConfig::default() }; ``` ## Behaviour - **Connecting.** `consume` connects first and returns `FailedToConsumeDatasource` if that fails, which stops a pipeline that has no other datasource. - **Replay.** With `replay_enabled`, the datasource adds an internal slot subscription and remembers the last slot it saw. On reconnect it sets `from_slot` to that slot for `Confirmed` and `Finalized`, or to 31 slots earlier for `Processed` (and when `commitment` is `None`). Messages from the resumed slot can arrive twice; add a [deduplication filter](https://carbon.sevenlabs.org/concepts/filters.md) if your processor isn't idempotent. - **Updates.** Same mapping as [Yellowstone](https://carbon.sevenlabs.org/datasources/yellowstone-grpc.md#behaviour): account messages become `AccountUpdate` or `AccountDeletion`, transaction messages become `Transaction` with `is_vote` and `index` from Geyser, and block messages expand into transactions and accounts. Failed and vote transactions pass unless your filter excludes them. No `BlockDetails` are emitted. - **Reconnects.** After the stream ends, errors or fails to subscribe, the datasource waits 3 seconds and subscribes again. After 10 consecutive failed attempts it logs `Max reconnection attempts reached: 10` and stops, which shuts down a pipeline that has no other datasource. A successful subscription resets the count. There is no inactivity timeout: a connection that stays open but silent is not detected. - **Backpressure.** Updates use `try_send` and are dropped with `Failed to send … ` when the pipeline channel is full. - **Metrics.** Counters `laserstream_account_updates_received_total`, `laserstream_account_deletions_received_total`, `laserstream_transaction_updates_received_total`; histograms `laserstream_account_process_time_nanoseconds`, `laserstream_account_deletion_process_time_nanoseconds`, `laserstream_transaction_process_time_nanoseconds`. ## Troubleshooting ### The pipeline exits with `FailedToConsumeDatasource("gRPC transport error: …")` The first connection failed. Check the regional endpoint URL, including `https://`, and your network. ### `Failed to subscribe, will retry after 5s delay` The subscription was rejected, usually because the API key is wrong or the plan doesn't include LaserStream. The actual delay is 3 seconds; after 10 failures the datasource stops. ### `from_slot` has no effect You set `replay_enabled: false`. The datasource only sends `from_slot` when replay is enabled. ### Duplicate transactions after a reconnect Expected with replay. Deduplicate by signature, or make writes idempotent (for example, upserts keyed by signature). ### The stream stops without an error There is no inactivity timeout. Monitor `laserstream_transaction_updates_received_total` (see [Prometheus](https://carbon.sevenlabs.org/guides/prometheus.md)) and restart the process if it stops growing. ## See also - [Stream with LaserStream](https://carbon.sevenlabs.org/guides/stream-with-laserstream.md) - [Yellowstone gRPC](https://carbon.sevenlabs.org/datasources/yellowstone-grpc.md) for filter types and the full update mapping - [Filters](https://carbon.sevenlabs.org/concepts/filters.md) for deduplication - [Datasources concept](https://carbon.sevenlabs.org/concepts/datasources.md) and [update types](https://carbon.sevenlabs.org/concepts/updates.md) --- Carbon 2.0.0 documentation · Web: https://carbon.sevenlabs.org/datasources/helius-laserstream · Last updated 2026-11-09 · Index of all pages: https://carbon.sevenlabs.org/llms.txt